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Overturning Moments - Summing and Looping
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Joined: 25/09/2013(UTC) Posts: 325  Location: IL Was thanked: 19 time(s) in 17 post(s)
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Maybe it is because it is getting late and it has been a long week, but I just can't seem to program this in an elogant way. I have a force at a given elevation. I am trying to find the total moment at each elevation. See attached it should clear things up. Note I am ok with completely abandoning the technique I have shown.  Summing Overturning Moments.sm (11kb) downloaded 53 time(s). Thanks in advance!!
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Summing Overturning Moments [More].sm (21kb) downloaded 27 time(s).______________________________ I understand nothing about that field. At least you can populate for more points. The cumulative integral is my understanding. Maybe you just want the simpler additive Sum ? Jean
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Joined: 15/07/2010(UTC) Posts: 437   Location: Beer-Sheva Was thanked: 520 time(s) in 288 post(s)
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Rank: Advanced Member Groups: Registered
Joined: 25/09/2013(UTC) Posts: 325 Location: IL Was thanked: 19 time(s) in 17 post(s)
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I'm sorry, I must have been getting pretty tired. ioan has accurately described what I am trying to accomplish. Basically I'm trying to building a matrix with the total overturning moment at each floor due to the forces above. I actually didn't think to use a process like ioan has shown and it seems obvious now (although I still need to 'code' it). Basically the sum of the moments above plus the total shear force above applied at the top of the floor.
It looks like you guys have a couple of approaches that work, I just need to tweak them so that they can be adjustable based on a variable matrix size. Thank you!
I will give this approach a try.
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Rank: Advanced Member Groups: Registered
Joined: 25/09/2013(UTC) Posts: 325 Location: IL Was thanked: 19 time(s) in 17 post(s)
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@Ber7 -
The equation you proposed is something similar to what I had previously and I can't quite figure out how to adjust it so that it works at each floor.
The problem is that i starts at one and goes to whatever I define on top of the summation. However if I try to adjust the variable on top of the summation then I get the wrong answer. i.e. for the top floor i=1 the summation gives the moment for the bottom floor due to the force applied at the roof. However what I'm looking for is the overturning moment at the top floor (below the roof) due to the force at the roof. So i for Vsw needs to be 1 and i for Z.sw needs to be 5.
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Joined: 25/09/2013(UTC) Posts: 325 Location: IL Was thanked: 19 time(s) in 17 post(s)
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Joined: 03/02/2014(UTC) Posts: 67  Was thanked: 13 time(s) in 11 post(s)
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RFreund, For that last updated file you posted, isn't Msum=0 not needed? As well as summing Msum to whichever variable? Also shouldn't the vector of floor elevation be the same length as the vector for shear force? So that the first floor is at 13.5ft of elevation? Edited by user 30 October 2015 20:42:19(UTC)
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I agree with ioan92, it should be horizontal (or lateral) load. I also think that there is a force missing for one of the floors so that the elevation and force vectors are the same length. I entered it as 0kips in my example. The plot would look way better if it were shaded, but I have not taken the time to figure out how to do that. OM RFreund.sm (31kb) downloaded 26 time(s).Edited by user 31 October 2015 00:32:42(UTC)
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Rank: Advanced Member Groups: Registered
Joined: 03/02/2014(UTC) Posts: 67 Was thanked: 13 time(s) in 11 post(s)
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I was picturing the system like this: Forgive my ridiculous handwriting. 
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Joined: 25/09/2013(UTC) Posts: 325 Location: IL Was thanked: 19 time(s) in 17 post(s)
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Sorry, busy day today. Looks like you guys have it figured out. It is typical in my region to say "shear" because it is a 'shear'wall or the diaphragm shear due to lateral loads. However you are are correct, these are lateral forces (wind, EQ). Thanks again for your participation. I will give your functions and graph a try as they look much better than mine, but it appears that my "for" loop finally had the right answer (see "Summing Overturning Moments_2.sm" 
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Joined: 04/07/2015(UTC) Posts: 6,866 Was thanked: 981 time(s) in 809 post(s)
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I read you all collabs. I'm a bit "old timer", a problem that is not
pictured is not a problem. From 50 years recollection and more actual
"statistics", a 'momemt' is at least a product. Staitistical moment(s)
is/are often a bit more than a product.
Never mind my comment. Your problem is another way of expressing the
Eiffel shape [cross section of = pressure/traction].
Cheers, Jean.
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